Vitamins and minerals are called micronutrients. They are needed in much smaller amounts than protein, fat and carbohydrate but are essential for good nutrition. They help the body to work properly and stay healthy. Some minerals also make up part of the body's tissues, for example, calcium and fluoride are found in bones and teeth and iron is found in the blood.
Iron is a major component of
red blood cells and is necessary to keep all of the body's cells working
properly. Iron deficiency anaemia is the most widespread nutritional problem in
the world. It can be very serious in children and women of childbearing age,
especially during pregnancy, but it also affects men and older women. It leads
to lethargy (low work capacity), learning difficulties, poor growth and
development, and increased morbidity (illness) and maternal mortality,
especially at childbirth.
The best sources of iron are meat, fish, poultry, liver and other organ meats. Iron is also found in legumes, dark-green leafy vegetables and dried fruits, but this iron is not absorbed as well by the body as is the iron from animal products. Increasing the intake of vitamin C along with the vegetable sources of iron can help more of the iron to be absorbed and utilized.
Vitamin A is needed for
building and maintaining healthy tissues throughout the body, particularly eyes,
skin, bones and tissues of the respiratory and digestive tracts. It is also very
important for effective functioning of the immune system. Vitamin A deficiency
can lead to poor night vision (night blindness), severe eye lesions and in
severe cases permanent blindness. This occurs mainly in undernourished children,
especially those with measles and other infections. Vitamin A deficiency can
also lead to increased illness and death from infections.
Vitamin A is found naturally only in foods of animal origin, notably breast milk, liver, eggs and many dairy products. However, many dark-coloured fruits and vegetables contain pigments, called carotenes, that the body can convert to vitamin A. Foods rich in vitamin A include carrots, dark-yellow and orange sweet potatoes, mangoes and papaya.
Thiamin, riboflavin, niacin, vitamin B6, folate, pantothenic acid, vitamin B12 and biotin belong to what is sometimes called the vitamin B complex. The B vitamins are necessary for converting carbohydrates, fat and protein into energy and for using them to build and repair the body's tissues. Deficiencies of these vitamins can lead to serious effects including muscular weakness, paralysis, mental confusion, nervous system disorders, digestive problems, cracked and scaly skin, severe anaemia and heart failure.
Folate (folic acid, folacin) is needed to make healthy blood cells and its lack is a common cause of anaemia among women and young children. Folate deficiency during pregnancy can lead to birth defects.
Adequate daily intake of the B vitamins is important. Foods rich in B vitamins are dark-green vegetables, groundnuts, beans, peas, cereals, meat, fish and eggs.
Vitamin C is needed to increase absorption of dietary iron, to make collagen (connective tissue) which binds the body's cells together, and to serve as an antioxidant. Prolonged vitamin C deficiency can lead to scurvy. The signs of scurvy are bleeding gums and sore, swollen joints, and it can lead to death.
Most fruits, especially citrus and guava, and many vegetables, including potatoes, are good sources of vitamin C. Eating fresh fruit and vegetables is important for both adults and children.
Vitamin D is particularly important in the use of calcium by the body. Vitamin D is found in fish oils, eggs and milk, and is also produced by the body when the skin is exposed to sunlight. Lack of vitamin D can lead to rickets, a disease that causes soft and deformed bones in young children.
Calcium and phosphorus are important to body maintenance and to having strong healthy bones and teeth. Milk and dairy products are excellent sources of calcium and phosphorus.
Iodine is important for proper growth and development. Lack of iodine in the diet can cause goitre (swollen thyroid gland) and mental retardation. Iodine is found in seafood and in foods grown on iodine-rich soils. In areas where soils are low in iodine, steps should be taken to add iodine to the diet, usually through iodized salt.